1. Field of the Invention
The invention relates generally to the field of photographic cameras and in particular to a camera of the type wherein, when a release button or the like is manually depressed, a shutter is actuated to expose a section of film in the camera and a motorized drive is actuated to advance the film and re-set the shutter for the next exposure.
2. Description of the Prior Art
Typically in a number of motorized cameras adapted to receive a film cartridge containing a filmstrip having successive unexposed frames, such as 35 mm film, manual depression of the release button releases the shutter for opening and closing to expose a film frame positioned in alignment with the shutter. After the shutter is closed, the motorized drive is actuated to advance the filmstrip until a fresh frame is positioned in alignment with the shutter. Simultaneously, the motorized drive re-sets the shutter for the next exposure. Advancing the filmstrip and re-setting the shutter for the next exposure places a combined load on the motorized drive which is relatively high. This combined load is even higher during film initialization when the motorized drive must draw the filmstrip from the cartridge for the first time. When the filmstrip is pulled from the cartridge for the first time, the original film set and the original orientation of the plush fibers in the egress opening of the cartridge impose a break-away load on the motorized drive which is much higher than the pulling load imposed on the motorized drive after the original film set and the original fiber orientation have been altered to conform with film withdrawl from the cartridge. Thus in these prior art cameras the motorized drive may be pushed to its limit during film intialization because the drive must overcome both the film break-away load and the shutter re-setting load. This produces an excessive drain on the batteries used to power the motorized drive, and it can eventually cause the motorized drive to fail.
Recently, several 35 mm cameras have been commercially introduced in which the shutter is not released before the motorized drive is acuated to initialize the filmstrip. As a result, the motorized drive does not have to re-set the shutter during film initialization. This eliminates the shutter re-setting load which would otherwise be imposed on the motorized drive, and thereby allows the motorized drive to dedicate its full torque to overcoming the break-away load required to first pull the filmstrip out of the cartridge for the first time. Generally, in cameras of this type, for example the Ricoh model TF-200 camera, the motorized drive is actuated in response to closure of a rear door of the camera. A problem with those prior art cameras, however, is that once the rear door is closed film initialization must follow, it is automatic. Consequently, after the rear door is closed, the cartridge normally cannot be removed from the camera without exposing the filmstrip. This is undesirable because in certain instances the photographer may wish to replace the film type in the camera with a different type film before taking any pictures.